<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <script type="text/javascript">

           let obj = window.setTimeout(function(){
                alert("执行1次定义器功能")
            }, 300);

            clearTimeout(obj);

        </script>
        
    </body>
</html>